Various vane-type fluid displacement apparatuses have been proposed for use in certain limited applications. These proposed devices have primarily consisted of pumps, compressors, fluid driven motors, and fluid flow meters. Even in these limited applications, however, the vane-type apparatuses heretofore proposed have generally not performed satisfactorily and therefore have not gained significant acceptance. Common difficulties encountered with prior art vane-type apparatuses have included: an unsuitability for use with friction-reducing devices, which has traditionally limited their use to moderate power levels; a large fixed-surface to moving-surface contact area, resulting in high friction; an inability to withstand bending forces applied to the crankshaft; a reliance on discrete check valves or the like; and an inability to accommodate simultaneous reciprocating flow from each individual chamber.
U.S. Pat. No. 3,821,899 teaches a vane-type meter for use with petroleum or other fluid products. Its structure comprises: a housing having an inlet port and an outlet port; a rotating interior disc; an interior shaft held with respect to the rotating disk in a fixed, eccentric position with respect to the rotating disc; four radially extending, articulated vanes which rotate within the housing about the interior shaft; and four valving structures extending perpendicularly from the outer periphery of one side of the rotating disc. Each of the vanes includes an inner vane element consisting of: a substantially flat body; a single closed ring which extends from one end of the body and is rotatably positioned around the interior shaft; and an elongate, open C-shaped groove extending along the opposite end of the body. Each articulated vane also includes an outer vane element consisting of: a substantially flat body; an elongate pentil structure is formed along one end of the body and pivotably held in the C-shaped groove formed on the inner member; and a second elongate pentil structure formed along the other end of the body. The second pentil structure is pivotably held in one of the valving structures.
Fluid flow through the meter of U.S. Pat. No. 3,821,899 causes the disc, valving ports, and articulated vanes to rotate within the meter housing. As they rotate, the vanes form compartments which change in volume and through which known amounts of liquid are transferred from the inlet to the outlet of the device. Thus, the rotational speed of the device provides a direct indication of the fluid flow rate.
U.S. Pat. No. 2,139,856 discloses a pump or fluid-driven engine employing articulated vanes having shaped outer surfaces. The vanes form fluid chambers which continuously change in volume.
In one embodiment, the apparatus of U.S. Pat. No. 2,139,856 comprises: a housing; a cylindrical casing held in fixed position within the housing; a crankpin mounted in the casing for eccentric revolving movement; eight articulated, two-part vanes, each having an inner end pivotably connected to the crankpin and an outer end pivotably connected to the casing; eight flow ports provided through a sidewall of the displacement chamber; a flow chamber provided between the casing and the housing; and eight flow ports and associated check valves provided in the casing between the outer ends of the vanes.
In a second embodiment of the device of U.S. Pat. No. 2,139,856, the crankpin is held at a fixed eccentric position within the casing and the casing rotates within the housing. As the casing rotates about the eccentrically positioned crankpin, the compartments formed by the articulated vanes successively draw fluid from inlet ports formed through one of the flat sidewalls of the displacement chamber, and then discharge the fluid through one or more fixed ports in the housing. Each of the articulated vanes has either one or two closed rings formed on the inner end thereof. These inner closed rings are rotatably positioned around the crankpin.
Devices such as those proposed by U.S. Pat. No. 2,139,856 and U.S. Pat. No. 3,821,899 have several shortcomings. First, the devices fail to provide any adequate means for reducing frictional forces generated within the moving articulated vane assemblies. Additionally, the cost and complexity of the devices is significantly increased by the required use of completely separate fluid intake and discharge valve systems and/or port structures. Further, the devices provide no means for creating, accessing, and utilizing reciprocating flow regimes between adjacent pairs of articulate vanes. Also, the devices disclose no means for selectively configuring the vanes and displacement chambers in order to obtain specific desired flow patterns. Additionally, these designs have large and significant areas of metal-to-metal sliding contact with no means shown for reducing friction between the parts. (Consider, for example, the potential for friction to be generated between parts 15 and 24 in the Savage (U.S. Pat. No. 2,139,856) device; and between parts 18 and 42 in the Granberg (U.S. Pat. No. 3,821,899) patent. Finally, neither of these devices provide for bi-directional flow simultaneously from the various chambers.
A need also presently exists for a new or significantly improved power plant for light aircraft. Engine systems currently employed in such applications are expensive to manufacture, maintain, and overhaul, and produce excessive noise and vibration. Moreover, the existing systems are greatly inefficient and lose power at altitude. These efficiency and power problems lead to increased engine weight, increased drag, reduced available range and payload capacity, reduced air speed, reduced climb rate, and reduced aircraft ceiling. Broadly speaking, the stirling thermodynamic cycle offers at least a partial solution to the above problems. However, a conventional stirling engine suffers from a number of heretofore insurmountable problems, included among which is the difficulty in achieving an acceptable power to weight ratio--a difficulty which is due in part to the need for an improved means of coupling the pistons to the crankshaft.
Thus, what is needed is a vane-type device that experiences reduced frictional forces within its articulated vane assemblies. Additionally, the device should be one that can be assembled, operated, and maintained cost effectively. Further, the device should be capable of generating or responding to reciprocating flow during its operation. Even further, the vanes of the device should be configurable so that specific flow patterns can be obtained. Also, the vanes of the device should be positionable to reduce bending moment on the crankshaft. Additionally, the device should be one that, if used as an engine, is more fuel efficient and produces less noise and vibration during operation. Finally, the device, if used within an aircraft engine, should result in an engine that is less susceptible than conventional aircraft engines to power loss at altitude.
Before proceeding to a description of the instant invention, however, it should be noted and remembered that the description of the invention which follows, together with the accompanying drawings, should not be construed as limiting the invention to the examples (or preferred embodiments) shown and described. This is so because those skilled in the art to which the invention pertains will be able to devise other forms of this invention within the ambit of the appended claims.